weird noise out of the amp *not from headphone*

[Kai]

Hello all,
earlier today I was letting the amp run free with a hd800 to burn in the amp.
Since I wasn't listening to the phones, I noticed a very weird noise coming out of the amp.
It sounds kind of like a clicking sound. It also reminds me the sound when you create an arc between two conductors...scary scary..

Please note the following:
*This sound only comes out of the amp, not through the headphones;
*This sound is not loud at all, in fact if there is any other form of sound source in the room, one would not be able to hear this noise;
*This sound would randomly start and stop, I found one way to trigger this sound is to switch the auttenuators. Immediately after you change the volume, this sound would come out and disappear within half second.

I will try to attach a wav file recorded by a sony D50, in order to hear this sound, one need to turn up the volume of their speaker/phones (might try to use an IEM, as this noise really is hard to hear). In this record, you will hear me switching the auttenuators, and right after the switch the sound will come out.

On the other hand, I found no trouble listening music through this amp at all. I don't know if this is normal, and if I should be worried..

Thanks everyone!

Kai

[Paul Birkeland]

It could very well be a bit of microphonics from the switch clicks returning through the 6C45's.

[Kai]

It could very well be a bit of microphonics from the switch clicks returning through the 6C45's.

Would it be normal to have this noise though? This noise would also come out randomly even if the attenuators are untouched.

Kai

[Paul Birkeland]

Well, I can't really hear any noises in your recording, but thermal changes in the tube glass can set this off a bit, as well as physical vibration.

-PB

[Kai]

Well, I can't really hear any noises in your recording, but thermal changes in the tube glass can set this off a bit, as well as physical vibration.

-PB

PB, it is very hard to hear this noise. I had to turn my speakers up by a lot in order to hear it. On the other hand, this sound can be heard by using a pair of IEM a lot easier...

[TubeTim]

....
It sounds kind of like a clicking sound. It also reminds me the sound when you create an arc between two conductors...scary scary..
.....

If it sounds like an arc, I would check in a darkened room to see if you visibly see any arcs are visible.

Statement of obvious, don't reach near the 'hot' chassis with the lights off.

_ .. --
  TiM